The API ratings you find on the bottles of oil start with letters like "SJ, SM" etc or with "CJ, CK, etc?
The 'S' stands for "Spark Ignition" as in gasoline engines. The 'C' stands for "Compression Ignition" engines as in diesels.
They're all supposed to be backward compatible. Yeah. Right.
Back in the 80's, the EPA (one of my absolute favorite government bureaucracies) discovered that the ZDDP (zinc) in engine oils was destroying catalytic converters. So they made the refineries take it out. No more ZDDP.
Problem was, back then, most engines still had flat tappet camshafts and the ZDDP was required/desired to help lubricate them. So people started blowing camshafts more often.
I even remember the rash of blown up engines in NASCAR events (I call them naGMar anymore) because the oil companies didn't think to tell them (even the ones with their own brand names on them). I have grown out of watching naGMar. Incredibly boring watching the same body, the same....... nevermind
Also a reason gas engines back then were rev-limited so low. But not the only reason by far.
When the EPA forced refiners to go to the new CK diesel oils, Ford had kittens. They sent out notifications to all their Power Stroke owners to NOT use the oil. They refused to certify the new API rating for any of their vehicles. Said it was too thin.
The EPA won that battle.
But, since SJ rated diesel oil has been all used up by now........ :confused3:
I use synthetic in everything. Everything. Even my lawnmower. Is it worth it? I think so.
Some of my buddies insist on being troglodytes and refuse to enter the 21st century. A few of them with good reason. Some work their diesels so hard and so often, it hardly matters what you put in them. It needs to be changed ever three months or so. And they work them so hard, pulling such loads every day that synthetic isn't worth the hassle. They usually buy their oil in drums, anyway
But for the average shmoe? I recommend synthetic oil.
On my Cummins turbo diesel, I get 21 MPG (empty) on the highway. Hand checked. On long trips. Around town...... Meh? 16 or thereabouts.
Sorry to get so involved but you need to buy 'C' rated oil for a diesel. Somewhere, some engineer can tell you why. But just do it.
Personally, I'm a believer in lower weight synthetic oil (5w 40). It gets moving earlier and better when your engine is cold (which is when you do the damage to your engine -- When it's cold), it takes the heat better, Dino oils can beak down into useless goo at around 250 degrees, Synthetic is good for a lot more. And, it lubricates better than dino oil.
Why wouldn't you want to use a good synthetic in your diesel??
Just my :twocents:
And worth even less:dance1:
